Deodorants are preparations which have antimicrobial activity and which mask, remove, or decrease perspiration odor. Antiperspirants are substances which have astringent action and inhibit the flow of perspiration. Salts of metals such as aluminum, zirconium, zinc, etc. have astringent properties and are often used in antiperspirants. When these salts are mixed into standard vehicles and applied to the skin, perspiration flow is inhibited as long as the antiperspirant salts remain on the applied area. However, the length of time an antiperspirant is effective depends largely on how profusely an individual sweats. The excretion of sweat tends to wash away the antiperspirant salts and thus reduce the effectiveness of an antiperspirant formulation. Obviously the rate at which antiperspirant salts wash away correlates directly with the degree to which an individual sweats.
Thus a means of providing more effective, longer lasting antiperspirants is definitely of interest.
Microencapsulation is a process by which a given substance or material is protected or separated from its surrounding environment in a protective covering. Microencapsulation of certain core materials is often desired to facilitate controlled release of the microcapsule contents into a specified environment. Time release microcapsules release their core materials at a controlled rate. The result is that the core material has a longer effective life since it is released from protective microcapsules at different times. The benefits of controlled release are obvious. For example, when pharmaceuticals are in the controlled release format, it generally allows the user to ingest or apply one long acting dose of drug instead of being obliged to ingest or apply many small doses of drug throughout a time period.
The microencapsulation of fragrances, inks, and a myriad of other substances is known in the art. Fragrance microcapsules are often found in scratch and sniff inserts in magazines, in perfumes, deodorants, and host of other applications.
There are many obvious advantages in microencapsulating antiperspirant salts. Antiperspirant salts sometimes cause skin irritation in sensitive individuals. Wince the internal constituents of microcapsules are insulated from the surrounding environment (i.e. skin), and released only when needed, skin irritation may be substantially alleviated in susceptible individuals. Microencapsulation of antiperspirant salts also provides for controlled release of the internal constituents, hence lengthening the effective period of the antiperspirant. However, antiperspirant salts are difficult to encapsulate due to their acidic nature. Up until now it has been found that most antiperspirant salts rapidly degrade or react with the substances used to form the outer shell of the microcapsule. Microcapsules can also be washed away by sweating just as antiperspirants salts, so a means of keeping the microcapsule securely anchored to skin is also desireable.